I have one for my CZ-75b. Trust me, the ATF unannounced inspection is an urban myth.
Friend of mine owns two gun shops - they go in there all the time unannounced.
The ATF is too busy running stings on companies like mine. A while back they sent some weirdo to my machine shop asking if he could “rent” my machines to finish some 80% lowers. I told him hell no. A few days later here comes our trusty ATF agents announcing “we heard you’re making guns here.” I told them they are trespassing and unless they have a warrant they are not allowed in my shop. It turns out nearly every machine shop had the same visit.